Automatic reset brake release



March 14, 1961 E. G. ROEHM AUTOMATIC RESET BRAKE RELEASE 2 Sheets-Sheet1 Filed March 5, 1958 ...111| lll. 7

March 14, 1961 E. G. ROEHM 2,974,756

AUTOMATIC REsET BRAKE RELEASE Filed March 3, 1958 2 Sheets-Sheet 2United `States Patent AUTOMATIC RESET BRAKE RELEASE Eldron G. Roehm,Dayton, Ohio, assigner to The Reliance Electric and Engineering Company,Cleveland, Ollio,la corporation of Ohio uFi'lea Mar. s, 1958, ser. No.718,688

.4 claims.' (cl. 18s- 171) This invention relates to brakes for electricmotors, and particularly to a manual brakerelease and automatic resettherefor.

In the electric motor art itis known to control rotation of the motorshaft through use of a brake, usually a friction type' brake, whichoperates or is eifective only when they motor is stopped orde-energized, it being the object of such `a brake to inhibitinadvertent rotary displacement 'of the motor shaft when the motor isidle or stopped. According to one concept of brakes of this class, thefriction brake-is automatic in operation, being applied simultaneouslywith de-energizing of the motor and being released simultaneously withenergizing or starting of the motor. However, for purposes of test,adjustment and the like it is sometimes desirable to release the brakewhile the motor is stopped whereby to free the shaft for rotation.

The object of the invention is to simplify the construction as well asthe means and mode of operation of motor brakes, whereby such brakes maynot only be economically manufactured, but will be more efficient andsatisfactory in use, adaptable to a wide variety of applications, and beunlikely to get out of order.

it is a further object of this invention to provide for selectiverelease of the motor brake through a manual control mounted for readyaccessibility on the exterior of the motor housing. 1

Another object of the invention -is to provide for automatic restoringof the brake to the normal brake controls, in conjunction with theautomatic resetting of the external manual control.

A further objectief the invention is to obviate the use of a pluralityof brake release assemblies, it being pro-v With the .above and otherincidental objects in'view as'l will more lfully appear in thespecificatiomthe invention intended to be protected by Letters Patentconsists of the features of construction, the parts and combinationsthereof, and the mode of operation as hereinafter described orillustrated in the accompanying drawings, or their equivalents.

Referring lto the accompanying drawing wherein is shown one butobviously not necessarilyl the only form of embodiment of theinvention,v

Fig. 1V is a view in longitudinal section through one end 2,974,756Patented Mar. 14, 1961 of an electrical motor showing a brake mechanismand the release controls therefor in accordance -with the illustratedembodiment of the invention, Fig. l being taken along an irregular lineas indicated at 1-1 in Fig. 2;

Fig. 2 is a view in cross section taken substantially along the line 2-2of Fig. l;

Fig. 3 is a vview in cross section, taken substantially along the line3-3 of Fig. l

Fig. 4 is a view in horizontal section taken substantially along theline 4-4'of Fig. 2;

Fig. 5 is a view similar to Fig. 4 but fragmentary in form and showingthe manual release control 4adjusted to its brake releasingposition;and. 1

Fig. 6 is a detailed view in front elevation of the'mo-J tor housing,vshowing the manual brake. release'controlthereon.

Like parts are indicated by similar characters of refer` enceYthroughout the several views.

Referring to the drawings, brake mechanism in accordance with theillustrated embodiment of the invention is an integral part of anelectric motor assembly. Thus, the motor housing includes a cylindricalend portion 101 adapted to what may be considered to be its inner end ishaft.

(the right hand end as shown) to be attached to the center or ield ringportion of the motor housing. The motor shaft 11 extends through andbeyond the housing 10 in approximately the center thereof, the housinghaving -a transverse partition 12 providing a bearing 13 for the Thewall 12 further provides a lateral extension 14 projecting toward theopposite or left hand end of the housing 10 and acting as a'seat for anannular body 15. The latter has a circumferential series of peripheraltangsr 16 (tFig. 3) which are in abutting relation to theouter orlefthand end of the housing portion 10, the body 15 being in effect receivedwithin such outer end of the housing. Through each of the tan'gs 16extends a longitudinal bolt 17 projecting through the housing 10 andtoward the opposite end of the motor where it is suitably anchored.. Theouter end of each bolt 17 is screw threaded; as indicated and a nut 18is turned thereon into engagement with a respective tang 16, theconstruction and arrangement of parts being such as to seat the body 15firmly upon he housing 10 so that it in eifect becomes a; part thereof.The threaded portions of the bolts 17 also receive nuts 19 at theirouter extremities by which there may be held over the outer end of thehousing 10 a cover member 21 which, as will be seen, surrounds andencloses the brake mechanism.

The outwardly facing side of the body 15 is formed with an annularchamber 22 in which is installed an electrically energizable coil 23. Inparallel adjacent relation to the outwardly facing side of the body 15is a friction brake assembly comprising spaced apart non-metallicfriction discs 24 and 25 mounted for unison rotation to` the peripheryof a hub number 26 keyed to the shaft 11 to rotate therewith. The `discs24 and 25 are suitablyconnected to the hub 26 asfor example byspliningas.

indicated. Between the discs 24 and 25 is a friction plate 27. Inflanking relation to the friction discs are a brake.

plate 28 and an armature plate Z9, the latter being adjacent to the body15 and covering the annular opening 22 assembly along the threaded studs31, and a nut 33 specifically limits outward movement of the armatureplate 29, both nuts being of course adjustable to vary the amounts ofpermitted motion.

A compression spring 34 is received in the center of the body 15, seatedon an internal ledge 35 therein and pressing against the armature plate29 in a direction to urge it youtwardly away from the body 15 and in -adirection to press the assembly of friction discs and plates upon thebrake plate 2S. The tendency of the spring 34, therefore, is Ytoeffectuate orto energize the brake mechanisrn and in the assemblyofparts a spring 34 is selected which when installed in the body 15between the ledge 35 and the plate 29 will be under compression Aso thata force is provided normally to apply .a braking pressure wherein thefriction discs 24 and 25 are squeezed between the several plates 27, 2Sand 129 whereby to inhibit Yrotation of the Ashaft 11. Under suchapplied braking pressure, the armature plate 29 takes lup a vpositionspaced from the adjacent face of the body I15. Energizing of the coil 23serves to retract the plate toward lsuch Vface and Vto seatfit thereon,further compressing `the spring 34 and removing the applied pressure inthe assembly of brake elements whereby the brake 'is in effect releasedand the shaft 11 is freeto turn. Upon de-energizing of the coil 23 thearmature 29 is returned to control of the spring 34 and reassumes aclamping relation -with respect to the brake disc assembly and soreapplies the braking 13.655.11.116-

The energizing and the de-energizing of the coil 23 may be individuallycontrolled, but it will be understood that this action will normallytake place in correspondence with the energizingnd de-energizing of themotor windings in order that the brake may be applied at the same timethat the motor is stopped and in order that the brake may be released atthe same time that the motor is started.V

For manual release of the brake in periods of motor idleness, which maybe desirable Vfor test, adjustment or like purposes, there is providedon the exterior of the housing Y1I] a handle 36 (see Fig. V6) rotativelyadjustable relatively to the housing. The handle 3 6 is a part of a camand handleassembly further comprising a cylindrical body 37 rotatablymounted in a through opening 38 in the wall of the housing. A reduceddiameter knurled stud 39 projects from one end of the body 37 to the eX-terior of the housing and the handle 36 is pressed thereon. From theopposite end of the body 37 there projects into the interior of thehousing an eccentrically positioned half round cam 41 formed by cuttingaway a part of the inwardly projecting end of the body. The ,body 37 isheld in position in the opening 38 by a plate 42 fastened to the outsideof the housing in surrounding relation to the reduceddiameter vstud 39by a screw 43. That part of the handle 36 facing the plate 42 isannularly recessed to receive a torsion spring 44 which at its one endis hooked around or anchored to the screw y43 and which at its other endis connected to the handle by means of an opening 45 therein. The spring44 tends to hold the handle 36 in the upright position illustrated andto resist turning motion thereof, such motion serving to tension thespring so 'that upon release of'the handle from a rotary adjustedposition the spring tends to turn or to reset the handle to its normalupright position. Rotary motion of the handle 36, it will be understood,is pai-taken of by the body 37 and eccentric projection 41 thereoninasmuch as the handle is in effect secured to the stud through theknurled stud 39.

yThe eccentric portion 41 of the cam and handle assem- -bly'underliesone end of a release plate 46 which normally rests upon spaced apartpads 47 and V48, integrally formed on the body 15 on what may beconsidered to be the in- Wardly facing side thereof. `Compressionsprings 49 are seated in the transverse wall 12 of the housing 10 andurge the release plate 46 to a seat on the pads 47 and 48. Intermediateits engagement with the pads 47 and 48, the

release plate `46 has an opening 51 through which the shaft 1'1 passes.`On opposite sides of the opening 51 are other, smaller diameter,openings 52 each providing for the passage therethrough of a rod 53extending inwardly in the housing from the armature plate 29. Thus, themid portion of the armature plate 29 is formed with a depressed portion54 having an opening 55 through which a shaft 11 passes. On oppositesides of the opening 55 the rods 53 are riveted or otherwise secured tothe depressed portion S4 of the armature plate in such manner that therods partake of the bodily shifting motions of the armature plate yasbefore described. The rods 53 are attached to the plate 29 at their oneends. Their opposite ends extend through respective openings 52 in therelease plate 46 and beyond such openings have limit rings 56 mountedthereon. f

As may be seen from the construction and arrangement of parts the rods53 are freely slidable in the release plate 46. Since the latter isnormally held to a seat on the body 15 by springs 49 it does not partakeof the normal shifting movements of the armature 29 as effected inresponse -to the energizing and de-energizing of the coil 23. In theposition of applied brake pressure, however, the limit rings 56 on therods 53 lie near to the release plate v46 so that a lifting orretracting movement of :the release .plate toward the transverse wall 12will serve through the rings 56 to pull axially upon the rods 53 andthereby to retract the armature plate 29. Motion of the plate 46 in thissense is accomplished by the cam like projection 41 on the body 37Which, as noted, underlies one end of the .plate 46. In response to atuming motion of the handle 36 lthe portion 41 rises to engage theunderside of the plate 46, and as turning motion of the handle -iscontinued, the plate 46 is lifted, pivoting about the far pad 48 of thepair of pads upon which it normally rests. The relationship of the partsis such as to provide for a limited amount of movement of the plate 46,which movement as transmitted through the rods 52 to the plate Y29 iseffective to retract the plate a part only of the distance by which-itisretractable by the coil 23 but a distance sufficient to release thebraking pressure. Accordingly, turning of the handle 36 in a rotarysense to raise the eccentric or cam portion 41 to its highest pointresults in a release of the braking action upon shaft 1-1, freeing suchshaft for rotation in the same manner as is effected by energizing ofthe coil v23. Further, since the retracting motion of the armature plate29 is accomplished against the urging of the spring 34, there is areactant yforce generated by the spring and through the plate 29, rods53 and plate 46 which is 'applied to the eccentric or cam portion 41 ina manner to resist return movement of the handle 36 to its 'normalupright position. The applied pressure is greater than that'exerted bythe torsion spring 44 with the'result that when the handle has beenturned to an operating position it will tend to remain in such position.The handle may be reset to normal manually and the brake therebyrestored to operation under pressure of vthe spring 34. Further inaccordance with the instant inventive concept, however, the resetting ofthe manual brake release control is van automatic operation occurringupon the next occasion of the energizing of coil 23. Thus, with thearmature plate 29 Ypartlyretracted as described and applying africtional holding pressure to the manual brake release, if the coil 23is now energized the plate 29 will be retracted to its vfullest extent.This motion tends to move the rods 53 relatively to the release plate 46with the result that the frictional pressure applied by this plate tothe eccentric portion 41 of the cam and handle assembly is relieved. Thespring 44 accordingly is enabled to return the cam and handle assemblyto its normal position as illustrated in Fig. 4, the operative positionof the parts being shown in Fig, 5. In the operation of a motor equippedaccording to the instant invention, therefore, should it be foundYnecessary to set the cam and handle assembly to release the brake in aperiod of engine idleness the assembly may simply be left in anoperating position and when the motor is next started the manual releasedevice will be reset to its normal position in consequence thereof andas a part of the same operation energizing the coil 23.

From the above description it will be apparent that there is thusprovided a device of the character described possessing the particularfeatures of advantage before enumerated as desirable, but whichobviously is susceptible of modiiication in its form, proportions,detail construction and arrangement of parts without departing from theprinciple involved or sacrificing any of its advantages.

While in order to comply With the statute the invention has beendescribed in language more or less speciiic as to structural features,it is to be understood that the invention is not limited to the speciiicfeatures shown., but that the means and construction herein disclosedcomprise but one of several modes of putting the invention into eiect,and the invention is therefore claimed in any of its forms ormodications Within the legitimate and Valid scope of the appendedclaims.

Having thus described my invention, I claim:

' l. 'In an electric motor, a housing, a shaft rotatably mounted in saidhousing, an electrically energizable coil surrounding said shaft, brakemeans to inhibit rotation of said shaft, including an armature plate onone side of said coil movable toward said coil in response to theenergizing thereof to release said brake means, spring means stressed bymotion of said armature plate toward said coil and returning said platein the opposite direction upon de-energizing of said coil, a releaseplate on the opposite side of said coil in parallel relation to saidarmature plate, rods interconnecting said armature plate, and saidrelease plate extending longitudinally of and through said coil, saidrods being connected at their one ends to said armature plate for unisonreciprocating motion and at their other ends to said release plate forunison motion in one direction only, means accessible from outside saidhousing to move said release plate in said one direction only and springmeans different from the first recited spring means urging said releaseplate in the opposite direction and stressed by operation of said meansoutside housing to move said release plate in said one direction.

2. In an electric motor, a housing, a transversely eX- tendingstationary wall in said housing, a shaft longitudinally disposed in saidhousing and rotatably mounted in said wall, an electrically energizablecoil mounted on said wall in surrounding relation to said shaft, brakemeans to inhibit rotation of said shaft, including an armature plateparallel to said Wall and disposed on one side of said coil to movetoward said coil in response to the energizing thereof to release saidbrake means, spring means stressed by motion of said armature platetoward said coil and returning said plate in the opposite direction uponde-energizing of said coil, a release plate on the opposite side of saidcoil, spaced apart pads on said transverse Wall providing a seat forsaid release plate,

spring means urging said release plate to fa seat on said pads, rodsinterconnecting said armature plate and said release plate extendinglongitudinally of and through said coil, said rods being connected attheir one ends of said armature plate for unison reciprocating motionand at ,their other ends to said release plate for unison motion only inresponse to a lifting of said release plate from said pads, and meansaccessible from outside the housing to lift said release plate a limiteddistance from said pads to draw said armature plate a correspondingdistance toward said coil, said release plate being returnable by saidspring means to a seat on said pads under control of said lift means.

3. In an electric motor, a housing, a transverse stationary Wall in saidhousing having a laterally projecting extension thereon defining aninner chamber in said housing, a body having a through longitudinalopening therein and seated on said flater-al extension, means rigidly tohold said body on said extension, a shaft longitudinally disposed insaid housing and rotatably mounted in said transverse wall, one end ofsaid shaft extending through said inner chamber and through and beyondsaid body, an electrically energizable coil mounted on said body andsurrounding said shaft, brake means to inhibit rotation of said shaft,including an armature plate outwardly of said coil and retractabletoward said coil in response to the energizing thereof to release saidbrake means, a spring mounted in said body to bear on said armatureplate and compressed by retracting motion of said armature toward saidcoil, said spring returning said armature plate in the oppositedirection upon deenergizing of said coil, a release plate disposed insaid inner chamber in generally parallel relation to said armatureplate, spring means urging said release plate toward said body to a seatthereon, rods interconnecting said armature plate and said release plateextending longitudinally of and through said body, said rods beingconnected at their one ends to said armature plate for unisonreciprocating motion and at their other ends to said release plate forunison motion of said release plate only in connection with a liftingthereof or in a direction aWay from said body, and means accessible fromoutside said housingto effect limited motion of said release plate asdescribed for a limited retracting of said armature plate toward saidcoil.

4. An electric motor according to claim 3, characterized in that saidbody provides spaced apart pads for the seating of said release plate,said last named means applying a lifting force to said plate at one sidethereof whereby said plate is lifted from one of said pads Whilepivoting on the other one thereof.

References Cited in the file of this patent UNITED STATES PATENTS596,097 Wellman Dec. 28, 1897 2,512,565 Hallander lune 20, 19502,851,129 Doerries Sept. 9, 1958 FOREIGN PATENTS 556,985 Great BritainOct. 29, 1943

